Influenza from the veterinary side

October 13, 2009

About two weeks ago, we had a scare with my infant daughter when she spiked a 106-degree temperature and subsequently had a seizure. She had been battling a cold, along with the arrival of her first tooth, so a mild fever was to be expected. We never imagined it would get so dangerously high.

While sitting in the emergency room, I racked my mind about what could have caused such a high fever for my daughter — pneumonia, meningitis, urinary tract infection, or possibly even the swine flu? She had upper respiratory symptoms, a fever, and certainly access to the flu virus via kids at daycare. Thankfully, all of her tests were negative. Her fever resolved with one dose of Motrin, and she was soon back to her normal self.

There are two types of influenza virus: Type A and Type B. Type A is found in humans and many animals, such as ducks, chickens, pigs and whales, while Type B circulates widely through humans. Type A viruses are most virulent to people and appear to have originated from birds.

Type A influenza viruses have persisted for millions of years in wild aquatic birds with no apparent risk to the birds themselves. However, the virus is highly versatile with capability to mutate, allowing it to jump from wild bird species to domesticated ducks and chickens. From there, the next stop in the infectious chain is to pigs.

Pigs can be infected by both bird (Type A) and human (Type B) strains of influenza. Pigs then act as an “influenza mixing bowl,” allowing bird and human strains to exchange genes. These new “mixed” strains can then become infective to people.

In 1997, for the first time, health officials found that one strain of bird influenza skipped the pig step and became directly infective to humans. It was a very lethal influenza known as avian flu (Type A subtype H5N1). Fortunately, this virus could only be transmitted from infected chickens to humans and not from human to human. Otherwise, the virus would have spread world-wide very quickly, similar to swine flu (Type A subtype H1N1).

In August 2009, Turkeys in Chile were found to be infected with the swine influenza strain. There is concern now that the avian and swine flu strains may combine to form a highly contagious, potentially lethal new strain of influenza.

If swine flu has the capability of infecting turkeys, what about our beloved pets? Can dogs and cats contract or spread the H1N1 flu to members of their human families? Most likely, not. To this date, there are no reports of domesticated pets being infected with the swine flu strain, but we are not naive to the fact that influenza is an ever-changing virus.

Cats and dogs do have influenza strains specific to them, with no apparent risk to humans. In 2004, cases of an unknown respiratory illness spread through racing greyhounds at a track in Florida. This respiratory illness was found to be caused by an equine influenza (Type A subtype H3N8) that mutated to infect dogs. Once mutated, the virus spread rapidly from dog to dog.

Symptoms of canine influenza include coughing, runny nose and fever. Most dogs recover with supportive care, much like their human counterparts, but a few may die from complications of the virus. There is now a vaccination recommended for dogs at high risk, such as those participating in events or housed in areas where the virus is endemic. According to my research, there are no current cases of canine influenza in Ohio.

As for cats, avian (H5N1) influenza has been reported in domesticated cats in Germany and Austria. These cats contracted the disease by feeding on H5N1 positive birds. There doesn’t appear to be transmission of the virus between cats, or from cats to humans, and risk for infection is very low for indoor cats.

Influenza has been around for many years, and will continue to be an inherent risk to humans as long as we live and work closely with animals. Vaccines for influenza are extremely safe, occasionally causing a mild grade fever and/or discomfort at the site of injection. With vaccinations, we can protect ourselves from these ever-evolving viruses, as well as protect our families and pets.

As for my little Doodle, she’ll be receiving both the regular flu and the swine flu vaccines. That frightful night at the emergency room made me feel so helpless about what could happen to my child. By having her vaccinated, I hope to have some control over the diseases she may encounter in her world.

Dr. April Shattuck practices at Delphos Animal Hospital. She may be contacted at